Following up on announcements at Sony's E3 press conference today, Kojima Productions gave its E3 2009 special site an update, adding in a second game:

Formally announced today by Hideo Kojima at Sony's E3 press conference, Metal Gear Solid Peace Walker brings the PSP a true sequel in the Metal Gear Solid series. Kojima himself is directing and desiging the title, and he's brought over the core staff from Metal Gear Solid 4

Players take control of Naked Snake in the 1970s, ten years after Metal Gear Solid 3. Aside from that, you'll have to speculate on the content of the game by viewing the E3 trailer at the above site.

The extremely lengthy block of text at the site reads:

"Stories tell of a legendary hero who, with Metal Gear in his command, had once waged war against the world. His name was Naked Snake, a.k.a. Big Boss. Now in response to a world hungry for answers, the truth behind his legend will finally be told.

"The era is the 1970's. Big Boss had stationed his 'Soldiers without Borders' in Colombia, South America, where he was approached by a visitor from Costa Rica, 'a Nation without a Military.' In the wake of the Cuban Missile Crisis, as Latin America became a key to maintaining the power balance between East and West , Costa Rica had miraculously managed to maintain its peace and neutrality. However, in various regions of the country, a mysterious armed force seemed to be engaging in suspicious activities.

Now, to preserve peace in this nation without a military, the "Soldiers without Borders" move into action. In time, they would come to be known as the founders of 'Outer Heaven.'

"Forge a new path and live the legend with "Metal Gear Solid Peace Walker," the first official "Hideo Kojima Game" for PSP!"